Grinding-mill



H. W. HARDINGE.

GRINDING MILL.

APPLICATION FILED OCT. 31, 1919.

1,388,462. Patented Aug. 23, 1921..

UMTED STATES HARRY W. HARDINGE, OF NEW YORK, N. Y., ASSIGNOR TO HARDING COMPANY, OF

NEW YORK, N. Y., A CORPORATION OF DELAWARE.

GRINDING-MILL.

Specification of Letters Patent.

Patented Aug. 2 3, 1921.

Application filed Gotober 31, 1919. Serial No. 334,763. i

To all whom it may concern:

Be it known that I, HARRY W. HARDINGE, a citizen of the United States, residing at New York, county and State of New York, have invented certain new and useful Improvements in Grinding-Mills, of which the following is a full, clear, and exact description.

This invention relates to grinding mills of the ball and pebble type and has for its principal object to provide novel forms of grinding members employed in such mills.

In grinding mills of the above mentioned type the efficiency of such machines depends on the rapidity of grinding a given quantity of material to a given degree of fineness which in turn depends on :the aggregate grinding surface of the grinding members employed. In the motion of the mill the last mentioned members are continuously agitated or displaced with respect to each other and the material operated upon is ground between adjacent surfaces of said members. It has been proposed to employ grinding members in the form'of balls or spheres. Such members while practically operable and useful do not attain the maximum possible efficiency for the reason that the effective grinding surface between adjacent spheres is small. It has also been proposed to employ grinding members in the form of cylinders but the efficiency is not as greatly enhanced thereby as might at first be expected. One reason for this is that in the operation of the mill edges of certain cylinders come into contact with elements of adjacent cylinders and remain in this relationship for an appreciable length of time thus materially reducing the effective grindin surface.

n order to render the total effective grinding surface a maximum I have devised a form of grinding member which comprises oppositely extending cone portions. I wish to have it understood that, throughout this specification and claims, I employ the word cone in the generic sense in which it is employed in geometry, z. e., as applying to any solid included by a surface generated by the movement, according to any law, of an indefinite line, one point of which is fixed. This definition, it will be noted, is broad enough to include pyramids as well as circular cones.

Referring to the drawings which illustrate what now consider preferred form of my invention:

Figure 1 is a detail elevation, partly in section, of a drum of one form of grinding mill in which my grinding members may be employed.

Fig. 2 is an enlarged elevation of one form of grinding member.

Figs. 3 to 7 are similar views illustrating modified forms of grinding members.

Fig. 8 is an end elevation of the members shown in Fig. 7.

ile my invention may be employed in combination with various forms and types of mills, I have selected for the purpose of illustration a conical mill. Referring to Fig. 1, a drum 1 having an inlet portion 2 and a conical outlet portion 3 is adapted to be rotated on the hollow trunnions 4, 5. The material to be ground (not shown) is introduced through the trunnion 4: and leaves at 5. A multiplicity of grinding members 6 are contained in the drum 1 and on rotation thereof are adapted to grind the material located between said members. Each of these members is shown in Figs. 1 and 2 in the form of a solid comprising circular cones placed base to base.

It will be seen that the effective grinding surface between the grinding members is comparatively of a high magnitude. Although in the rotation of the drum the apices of certain of the members will contact with the elements or apices of others of said members, this relative position is an exceedingly unstable one and can endure for only a very brief time interval. When such contact occurs the members 6 will quickly adjust themselves to the relative position shown in Fig. 1 in which the effective grinding surface is a maximum.

The members 6 may be made of any suitable or desirable material. Thus cast iron has been commonly employed. In employing material of this specific nature, it is desirable that shrinkage strains in the members be relieved. To relieve such strains each member 6 may be provided with an axial bore or opening 7 as shown in Fig. 3. If desirable a reinforcing core 8 of copper, steel or other suitable material may be provided in the bore 7 and brazed, welded, cast, or otherwise secured to the body portion of each of said members. This arrangement, which is illustrated in Fig. 4, possesses the additional advantage of holding the body portion together in the event that cracks develop therein.

The construction of the members 6 may be modified in many ways without departing from the spirit of the invention. For example, instead of the oppositely extending cones being placed base to base as shown in Fig. 1, a more or less short cylindrical portion may be interposed between the bases of the cones. Such a member is illustrated at 6 in Fig. 5, the cylindrical portion may be interposed between the bases of the cones. Such a member is illustrated at 6 in Fig. 5, the cylindrical portion being designated 9. Furthermore the lateral surface may be ribbed as indicated at 10 in Fig. 6, or, if desirable, instead of providing circular cone portions each member may comprise cone portions in the form of pyramids. In Figs. 7 and 8 I have illustrated a grinding member 6 comprising oppositely extending hexagonal pyramids. Other modifications will occur to those skilled in the art and need not be illustrated.

What I claim is:

1. A rinding mill unit comprising a substantial y integral body having conical ends and a central bore.

2. A grinding mill unit comprising a substantially integral body havin conical ends and a central bore, and a rein orcing core in said bore.

3. A grinding mill comprising in combi nation, a rotatable container having therein a plurality of freely and individually tumbling grinding members, each of said members comprising oppositely extending cone portions.

4. A grinding mill comprising in combination, a rotatable container having therein a plurality of freely and individually tumbling grinding members, each of said members comprising oppositely extending cone portions, having an opening extending therethrough from tip to tip.

5. A grinding mill comprising in combination, a rotatable container having therein a plurality of freely and individually tumbling grinding members, each of said members comprising oppositely extending cone portions, having an opening extending axially therethrough and a reinforcing core in said opening.

6. A grinding mill comprising in combination, a rotatable container having therein a plurality of freely and individually tumbling grinding members, each of said members having oppositely extending co-axial circular cone portions.

7 A grinding mill comprising in combination, a rotatable container having therein a plurality of freely and individually tumbling grinding members, each of said members having oppositely extending circular cone portions secured base to base.

8. A grinding mill comprising in combination, a rotatable container having therein a plurality of freely and individually tumbling grinding members, each of said members being a solid of revolution and having oppositely extending cone portions.

In testimony whereof I hereunto afiix my signature.

HARRY W. HARDINGE. 

